Rihanna has let another person's needle inject her flesh with its inky liquid once again!

A recently posted Instagram picture of the precious Diamond smoking a blunt while posing in a bathing suit in Hawaii RIGHT before her 25th birthday ALSO reveals a brand new tattoo on the popstar's left bum-cheek (above)!

The tat is written in some foreign language, and seeing as we are NOT an expert in linguistics, we don't know where the letters come from or what they say.